Celgene buys Juno, Twitter dips, AIG buys Lloyds' parent

Juno Therapeutics (JUNO): Shares are surging in early trading, up over 25%. After several rounds of speculation, Celgene has finally purchased the shares of Juno it didn’t already own for $87 a share in a deal valued at $9 billion. Celgene bought a 9.7% stake in Juno back in 2015.

Twitter (TWTR): Shares are trading down around 2%, with the stock off about 7% in the last week. Monday’s news? The Wall Street Journal is reporting Twitter COO Anthony Noto is considering leaving the company to take the CEO role at finance startup SoFi.

Validus Holdings (VR): The stock is up 44% in early trading after news that AIG will buy the re-insurer for $68 a share in a $5.56 billion deal. Validus is the parent of Lloyds of London, among other subsidiaries.

For more on today’s big stock movers check out the Final Round, live at 3:55 p.m. Eastern, right here on Yahoo Finance.